Signaling for cartilage

November 27, 2006

Skeletal progenitor cells differentiate into cartilage cells when one master gene actually suppresses the action of another, said Baylor College of Medicine researchers in a report that appears online in the journal Proceedings of the National Academy of Sciences.

Skeletons are made of bone and cartilage cells that are differentiated from the same multipotent stem cell, said Dr. Brendan Lee, associate professor of molecular and human genetics at BCM, director of the Skeletal Dysplasia Clinic at Texas Children's Hospital and a Howard Hughes Medical Institute investigator. This same stem cell gives rise to bone, cartilage, fat and fibroblasts.

"The big question is what are the master genes that make a stem cell go one way versus another," said Lee.

Both SOX9 and RUNX2 are master transcription factors involved in the process of differentiating bone and cartilage.

The master protein SOX9 directs skeletal progenitor cells to become cartilage and another master protein, RUNX2, directs such cells to become bone, However, he said, the primordial skeletal cell has both RUNX2 AND SOX9.

"We then asked a simple question: Could these master transcription factors (that direct the expression of other genes) directly affect one another's function"" he said. After studies in the laboratory, with mice and with humans, the answer was yes.

"SOX9 appears to be the dominant player," said Lee. "When it is present in a progenitor cell, it turns off RUNX2 and allows the cell to become cartilage."

That does not answer the question of how such cells become bone.

"Clearly, something must turn off SOX9," said Lee. "That's the next question we have to answer."

Working in a genetic lab allowed Lee and his colleagues to learn from gene-caused diseases of the skeletal system. Studies of human tissues proved that the protein activity identified in cells in the laboratory and in studies with mice occurred in humans as well.
-end-
Others who took part in the research include Drs. Guang Zhou, Qiping Zheng, Feyza Engin, Elda Munivez, and Yuqing Chen of Baylor College of Medicine; Eiman Sebald of Cedars Sinai Medical Center in Los Angeles; and Deborah Krakow of the David Geffen School of Medicine, University of California, Los Angeles.

Funding for this research came from the National Institutes of Health and the Baylor College of Medicine Mental Retardation and Development Disability Research Center.

Baylor College of Medicine

Related Stem Cell Articles from Brightsurf:

Fat cell hormone boosts potential of stem cell therapy
Mesenchymal stem cell (MSC) therapy has shown promising results in the treatment of conditions ranging from liver cirrhosis to retinal damage, but results can be variable.

Oncotarget Characterization of iPS87, a prostate cancer stem cell-like cell line
Oncotarget Volume 11, Issue 12 reported outside its natural niche, the cultured prostate cancer stem cells lost their tumor-inducing capability and stem cell marker expression after approximately 8 transfers at a 1:3 split ratio.

Stem cell identity unmasked by single cell sequencing technology
Scientists from The University of Queensland's Diamantina Institute have revealed the difference between a stem cell and other blood vessel cells using gene-sequencing technology.

It's all about the (stem cell) neighborhood
Researchers at Duke-NUS Medical School have now identified how the stem cell neighbourhood, known as a niche, keeps stem cells in the gut alive.

Spaceflight activates cell changes with implications for stem cell-based heart repair
A new study of the effects of spaceflight on the development of heart cells identified changes in calcium signaling that could be used to develop stem cell-based therapies for cardiac repair.

Not just a stem cell marker
The protein CD34 is predominantly regarded as a marker of blood-forming stem cells but it helps with migration to the bone marrow too.

Interferon-beta producing stem cell-derived immune cell therapy on liver cancer
Induced pluripotent stem (iPS) cell-derived myeloid cells (iPS-ML) that produce the anti-tumor protein interferon-beta (IFN-beta) have been produced and analyzed by researchers from Kumamoto University, Japan.

Scientists aim to create the world's largest sickle cell disease stem cell library
Scientists at the Center for Regenerative Medicine at Boston Medical Center and Boston University School of Medicine are creating an induced pluripotent stem cell (iPSC)-based research library that opens the door to invaluable sickle cell disease research and novel therapy development.

Designer switches of cell fate could streamline stem cell biology
Researchers at the University of Wisconsin-Madison have developed a novel strategy to reprogram cells from one type to another in a more efficient and less biased manner than previous methods.

Allen Institute for cell science releases gene edited human stem cell lines
The Allen Institute for Cell Science has released the Allen Cell Collection: the first publicly available collection of gene edited, fluorescently tagged human induced pluripotent stem cells that target key cellular structures with unprecedented clarity.

Read More: Stem Cell News and Stem Cell Current Events
Brightsurf.com is a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for sites to earn advertising fees by advertising and linking to Amazon.com.